Image sensors are widely used in digital still cameras, cellular phones and security cameras, as well as medical, automobile, and other applications. The twin demands of higher resolution and lower power consumption have encouraged further miniaturization and integration of image sensors, and the technology used to manufacture the sensors, especially complementary metal oxide semiconductor (“CMOS”) image sensors, has continued to advance at great pace to meet the demands. The portable nature of many devices in which image sensors are used means that they are battery-powered, and that places particular emphasis on reducing image sensor power consumption so that the device's battery life can be as long as possible. Despite substantial advances in lowering power consumption of the image sensors, ways remain for further reduction in power consumption.